| 大陆板内玄武岩数据挖掘:成分多样性及在判别图中的表现 |
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| 引用本文： | 王金荣,潘振杰,张旗,陈万峰,杨婧,焦守涛,王淑华.大陆板内玄武岩数据挖掘:成分多样性及在判别图中的表现[J].岩石学报,2016,32(7):1919-1933. |
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| 作者姓名： | 王金荣 潘振杰 张旗 陈万峰 杨婧 焦守涛 王淑华 |
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| 作者单位： | 兰州大学地质科学与矿产资源学院, 甘肃省西部矿产资源重点实验室, 兰州 730000,兰州大学地质科学与矿产资源学院, 甘肃省西部矿产资源重点实验室, 兰州 730000,中国科学院地质与地球物理研究所, 北京 100029,兰州大学地质科学与矿产资源学院, 甘肃省西部矿产资源重点实验室, 兰州 730000,兰州大学地质科学与矿产资源学院, 甘肃省西部矿产资源重点实验室, 兰州 730000,中国科学院地质与地球物理研究所, 北京 100029,兰州大学地质科学与矿产资源学院, 甘肃省西部矿产资源重点实验室, 兰州 730000 |
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| 基金项目： | 本文受中央高校基本科研业务费项目（Lzu-Jbky-2012-128）及中国地质调查局项目（121201011000150012-02）联合资助. |
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| 摘 要： | 通常认为,大陆溢流玄武岩(CFB)、裂谷玄武岩(CRB)、板内玄武岩(WPB)均产于板内构造环境,其地球化学特征与OIB类似,源于富集的下地幔,与地幔柱的活动有关。本文利用GEOROC数据库对全球CFB、CRB和WPB数据进行挖掘,发现上述三类玄武岩判别图投图几乎落入了全部的构造环境域,有些甚至主要落入MORB和IAB区,而不是落入WPB区。结果表明原先的玄武岩判别图的判别功能值得商榷,尤其对大陆玄武岩来说,许多判别图都存在问题。全体CFB、CRB和WPB的地球化学成分变化巨大,暗示其源区具有强烈的不均一性:部分CFB、CRB和WPB来自富集的地幔柱,仍然具有经典的OIB的特征;部分来自MORB的源区,与MORB的再循环作用有关;部分来自岛弧岩石圈之下的亏损地幔源区,以强烈亏损Nb-Ta为特征,类似岛弧玄武岩的地球化学特征。许多地区的大陆玄武岩可分为低钛和高钛两类,低钛玄武岩大多是亏损或强烈亏损的,而高钛玄武岩通常是富集型的。本文的研究表明,富集型大陆玄武岩可能来自富集的下地幔,而亏损的和强烈亏损的玄武岩可能来自具有MORB或岛弧特征的软流圈地幔。进一步指出,源区性质可能是大陆玄武岩多样性的主控因素,其次为部分熔融程度、熔融深度、结晶分离、陆壳混染以及AFC过程。
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| 关 键 词： | 大陆溢流玄武岩 裂谷玄武岩 板内玄武岩 数据挖掘 亏损地幔 富集地幔 岛弧 |
| 收稿时间： | 2015/11/26 0:00:00 |
| 修稿时间： | 2016/6/14 0:00:00 |
Intra-continental basalt data mining: The diversity of their constituents and the performance in basalt discrimination diagrams |
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| WANG JinRong,PAN ZhenJie,ZHANG Qi,CHEN WanFeng,YANG Jing,JIAO ShouTao and WANG ShuHua.Intra-continental basalt data mining: The diversity of their constituents and the performance in basalt discrimination diagrams[J].Acta Petrologica Sinica,2016,32(7):1919-1933. |
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| Authors: | WANG JinRong PAN ZhenJie ZHANG Qi CHEN WanFeng YANG Jing JIAO ShouTao and WANG ShuHua |
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| Institution: | Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China,Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China,Institute of Geology and Geophysics, China Academy of Sciences, Beijing 100029, China,Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China,Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China,Institute of Geology and Geophysics, China Academy of Sciences, Beijing 100029, China and Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China |
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| Abstract: | It is generally considered that continental flood basalts (CFB), rift basalts (CRB), within-plate basalt (WPB) are produced in the plate tectonic setting which is related to the mantle plume activities from the enriched lower mantle, similar to OIB in terms of geochemistry characteristics. In this paper, a GEOROC database of the global CFB, CRB and WPB is used to find that these three categories almost fall in all various basalt tectonic environment areas, some even primarily falls in MORB or IAB, but not in WPB area. This result suggests that the original discriminant function of the basalt discrimination diagrams is still questionable, especially, there exist some problems in most of the discrimination diagrams of continental basalt. All these tremendous changes of CFB, CRB and WPB geochemistry compositions suggest that the source may be strongly heterogeneous: some of CFB, CRB and WPB come from enriched mantle plume with classic characteristics of OIB, some of them derive from MORB source related with the slab-recycled effect, and others from depleted mantle source beneath the island arc lithosphere, characterized by obvious Nb-Ta depletion, similar to island arc basalts. In many places, continental basalts can be divided into two types: low titanium and high titanium. Low-Ti basalts are depleted or strongly depleted, and high-Ti basalts are usually enriched. The study of this paper shows that enriched-type basalts may come from enriched lower mantle, but strongly-depleted-type or depleted-type basalts may derive from the astheospheric mantle characterized by MORB or IAB. The study further points out that the nature of the source may be the main controlling factor of the qualities of continental basalts. Meanwhile, there are many other important factors leading to the diversity of continental basalts, such as the degree of partial melting, melting depth, fractional crystallization, crustal contamination and AFC process. |
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| Keywords: | Continental flood basalt Rift basalt Within-plate basalt Data mining Depleted mantle Enriched mantle Island arc |
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